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參數(shù)資料
| 型號： | SP802SCN |
| 英文描述： | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| 中文描述： | 3.0V/3.3V低功耗微處理器監(jiān)控與電池開關(guān)過 |
| 文件頁數(shù)： | 14/20頁 |
| 文件大?。?/td> | 233K |
| 代理商： | SP802SCN |
SP690T/S/R DS/10 SP690T/S/R, 802/T/S/R, 804T/S/R, 805T/S/R Low Power Microprocessor Supervisory
Copyright 2000 Sipex Corporation
14
Switchover at V
(2.40V) ensures that battery-
backup mode is entered before V
gets too
close to the 2.0V minimum required to reliably
retain data in CMOS RAM. Switchover at higher
V
voltages would decrease backup-battery
life. When V
recovers, switchover is deferred
until V
rises above the reset threshold, V
,
to ensure a stable supply. V
is connected to
V
CC
through a 1.5
PMOS power switch.
Using a High Capacity Capacitor as a
Backup Power Source
Figure 21
shows two ways to use a High Value
Capacitor as a backup power source. The High
Value Capacitor may be connected through a
diode to the 3V input as in
Figure 21A
or, if a
5V supply is also available, the High Value
Capacitor may be charged up to the 5V supply
as in
Figure 21B
allowing a longer backup
period. Since V
can exceed V
while V
is above the reset threshold, there are no
special precautions when using these
μ
P
supervisors with a High Value Capacitor.
Operation Without a Backup Power
Source
These
μ
P supervisors were designed for
battery-backed applications. If a backup power
source is not used, connect both VBATTERY
and V
to V
. Since there is no need to
switch over to any backup power source, V
does not need to be switched. A direct connec-
tion to V
eliminates any voltage drops across
the switch which may push V
OUT
below V
CC
.
Replacing the Backup Battery
If V
is decoupled with a 0.1
μ
F capacitor
to ground, the backup battery can be removed
while V
remains valid without danger of
triggering RESET/RESET. As long as V
stays above V
SW
, battery-backup mode cannot
be entered.
Adding Hysteresis to the Power-Fail
Comparator
The power-fail comparator has a typical input
hysteresis of 10mV. This is sufficient for most
applications where a power-supply line is being
monitored through an external voltage divider
(refer to the
Monitoring an Additional Power
Supply
section).
If additional noise margin is desired, connect a
resistor between PFO and PFI as shown in
Figure 22A
. Select the ratio of R1 and R2 such
that PFI sees 1.25V when V
falls to its trip
point (V
). R3 adds the hysteresis and will
typically be more than 10 times the value of R1
or R2. The hysteresis window extends both
above (V
H
) and below (V
L
) the original trip
point (V
TRIP
).
V
CC
3.0V or 3.3V
GND
V
BATTERY
V
OUT
CONNECT TO
STATIC RAM
TO
μ
P
0.1F
CONNECT
pin 7*
1N4148
V
CC
3.0V or 3.3V
GND
V
BATTERY
V
OUT
RESET for the SP690T/S/R and the SP802T/S/R
*
CONNECT TO
STATIC RAM
TO
μ
P
0.1F
CONNECT
pin 7*
1N4148
+5V
Figure 21. Using a High Capacity Capacitor as a Backup Power Source
A)
B)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP804R | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP804RCN | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP804RCP | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP804S | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP804SCN | 3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP802SCN-L | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SP802SCP | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP802SEN | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
| SP802SEN-L | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SP802SEP | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:3.0V/3.3V Low Power Microprocessor Supervisory with Battery Switch-Over |
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